We recently released our ExcelFil TECH series of filaments alongside our ExcelFil ABS and PLA filaments. As we had some questions and feedback surrounding these composite materials here some additional information on them.
As composite materials can be a little harder to print than standard Plastic Filaments, we also will start a small series on how to configure the Slicer software and a couple of other processing tips and tricks to get good results.
What are Composite Materials?
Composite Materials are a mixture of a carrier polymer together with additional mix ins designed to enhance the material or visual properties of standard polymer filaments like ABS or PLA.
As Fused Deposition Modelling (FDM) relies on melting polymers and extruding them through a nozzle, they always require a carrier polymer to be able to be extruded. Due to its more convenient processing properties, a PLA compound is often chosen to which normally not FDM printable materials like Aluminium, Copper, Bronze or Wood particles are added. This will then change the properties and visual appearance of the printed objects.
These composite materials can exhibit quite some different properties to standard PLA. Our ExcelFil TECH Aluminium for example is a quite flexible, light weight, composite suited for example for applications like RC Multicopters or other models that benefit from these properties.
Ratio of compounding
We have chosen a compound ratio of a about (differs slightly by material) 70% polymer to 30% composite material. There are other composite materials on the market that claim much higher compound ratios. At first sight, it seems a higher ratio would be better. So why have we chosen a lower compounding ratio? Here are two main reasons one should consider when choosing the right composite filament for the application:
Avoiding Damage to printers
These composites can be quite abrasive. Most home and commercial 3D printers available on the market employ extruder configuration made of machined brass. Given the small diameters of these nozzles (typically 0.3-0.5mm) and having a very high ratio of composites can wear these nozzles extremely quickly. The nozzle diameter can get out of spec even after printing just one spool of some of the high ratio composites out there. As the slicer software is very dependent on having accurate information of the nozzle diameter, this will quickly lead to unpredictable print results. This fact often is hidden in the fine print of the product description or not even mentioned at all. If you look on google for “Nozzle Abrasive Filament” you will find many examples for this effect.
For some 3D printers it is quite easy to replace these nozzles, but for others this can be a very costly and annoying exercise. The only way to avoid this, is to replace the nozzle assembly with especially hardened steel or tungsten nozzle assemblies which might or might not be available for your printer type. The reputable hot-end manufacturer E3D for example provides these hardened nozzles for their extruders. Below an example image from their blog of the type of described nozzle damage caused by high-ratio abrasive composite filaments.
While this effect can not be completely avoided, we have not seen any dramatic changes to brass nozzle performance after printing 30-40kg of ExcelFil TECH metal composite filaments on our test printers.
Avoid lengthy Polishing and Post Processing
High ratio composites also require extensive polishing and post processing of the printed results. Granted, some of the results are quite astonishing, but these are only achieved after having access to expensive rock tumblers, applying polishing creams or spray paint to “weather” the printed objects. This can take from hours to days to achieve the superior results seen in some photos on the internet.
During beta testing our composites, we had quite some feedback that testers liked the fact that our materials did not require additional post processing or polishing. The picture below are (non Photoshop’ed) print results right off the print bed without any further post processing:
Our aim at Voltivo is to provide consumer grade filaments that are as easy and safely as possible to process.
While there are application that might yield slightly better visual results with higher composite ratios we believe that the potentially expensive damage to printers and time-consuming post processing outweigh the slight visual benefits that are achievable with higher compound ratios.
As always, we would love to hear your opinion on these thoughts. Please do not hesitate to leave a comment below or contact us directly with your feedback.